Certain vehicles can operate in one or more electric vehicle (EV) modes. In an EV mode, a high-voltage electric traction motor can be used as a prime mover. For example, an extended range electric vehicle (EREV) can be propelled by a fraction motor over a limited distance solely using battery power. Beyond a threshold range, a small internal combustion engine powers a generator to extend the effective EV range. A battery electric vehicle (BEV) operates exclusively in an EV mode, while a hybrid electric vehicle (HEV) selectively uses either or both of an internal combustion engine and a fraction motor(s) during different operating modes.
An electric drive system of the type used for establishing an EV mode typically includes a traction power inverter module (TPIM). The traction motors used for propelling the vehicle in an EV mode are typically configured as multi-phase AC induction or permanent magnet machines, while the battery module from which the traction motor draws electrical power is a high-voltage DC storage device. Reliable AC-to-DC and DC-to-AC power conversion is thus necessary. Various semiconductor switches or solid state devices within the TPIM are controlled to achieve the required power conversion. However, conventional control methods may be less than optimal under certain vehicle operating conditions and loads.